История Земли: Реконструкция геологического прошлого

Study of the geological history of Earth

Historical geology or palaeogeology is a discipline that uses the principles and methods of geology to reconstruct the geological history of Earth. Historical geology examines the vastness of geologic time, measured in billions of years, and investigates changes in the Earth, gradual and sudden, over this deep time. It focuses on geological processes, such as plate tectonics, that have changed the Earth's surface and subsurface over time and the use of methods including stratigraphy, structural geology, paleontology, and sedimentology to tell the sequence of these events. It also focuses on the evolution of life during different time periods in the geologic time scale.

During the 17th century, Nicolas Steno was the first to observe and propose a number of basic principles of historical geology, including three key stratigraphic principles: the law of superposition, the principle of original horizontality, and the principle of lateral continuity. 18th century geologist James Hutton contributed to an early understanding of the Earth's history by proposing the theory of uniformitarianism, which is now a basic principle in all branches of geology. Uniformitarianism describes an Earth formed by the same natural phenomena that are at work today, the product of slow and continuous geological changes. The theory can be summarized by the phrase "the present is the key to the past." Hutton also described the concept of deep time. The prevailing conceptualization of Earth history in 18th century Europe, grounded in a literal interpretation of Christian scripture, was that of a young Earth shaped by catastrophic events. Hutton, however, depicted a very old Earth, shaped by slow, continuous change. Charles Lyell further developed the theory of uniformitarianism in the 19th century. Modern geologists have generally acknowledged that Earth's geological history is a product of both sudden, cataclysmic events (such as meteorite impacts and volcanic eruptions) and gradual processes (such as weathering, erosion, and deposition). The discovery of radioactive decay in the late 19th century and the development of radiometric dating techniques in the 20th century provided a means of deriving absolute ages of events in geological history.

Geology is considered a historical science; accordingly, historical geology plays a prominent role in the field. Historical geology covers much of the same subject matter as physical geology, the study of geological processes and the ways in which they shape the Earth's structure and composition. Historical geology extends physical geology into the past.

Absolute dating allows geologists to determine a more precise chronology of geological events, based on numerical ages or ranges. Absolute dating includes the use of radiometric dating methods, such as radiocarbon dating, potassium–argon dating, and uranium–lead dating. Luminescence dating, dendrochronology, and amino acid dating are other methods of absolute dating.

The theory of plate tectonics explains how the movement of lithospheric plates has structured the Earth throughout its geological history.

Weathering, erosion, and deposition are examples of gradual geological processes, taking place over large sections of the geologic time scale. In the rock cycle, rocks are continually broken down, transported, and deposited, cycling through three main rock types: sedimentary, metamorphic, and igneous.

Paleoclimatology is the study of past climates recorded in geological time.

EonEraPeriodEpochsStart Phanerozoic Cenozoic Quaternary Holocene0.0117 Pleistocene2.558 Neogene Pliocene5.333* Miocene23.030* Paleogene Oligocene33.9* Eocene56.0* Paleocene66.0* Mesozoic Cretaceous Late Cretaceous100.5* Early Cretaceousc. 145.0 Jurassic Late Jurassic163.5 ± 1.0 Middle Jurassic174.1 ± 1.0* Early Jurassic201.3 ± 0.2* Triassic Late Triassicc. 235* Middle Triassic247.2 Early Triassic252.2 ± 0.5* Paleozoic Permian298.9 ± 0.2* Carboniferous Pennsylvanian323.2 ± 0.4* Mississippian358.9 ± 0.4* Devonian419.2 ± 3.2* Silurian443.4 ± 1.5* Ordovician485.4 ± 1.9* Cambrian541.0 ± 1.0* Proterozoic Neoproterozoic Ediacaran Precambrianc. 635* Cryogenian850 Tonian1000 Mesoproterozoic Stenian 1200 Ectasian 1400 Calymmian1600 Paleoproterozoic Statherian1800 Orosirian2050 Rhyacian2300 Siderian2500 Archean Neoarchean2800 Mesoarchean3200 Paleoarchean3600 Eoarchean4000 Hadean4567Historical geology